Senior police officers have been warned to look out for a new knife which can inject a ball of compressed gas into its victim that instantly freezes internal organs.

The 'wasp knife', which can deliver a ball of compressed gas capable of killing its victim at the press of a button, may be heading for Britain, the Metropolitan Police fear.

A needle in the tip of the blade shoots out the frozen ball of gas which instantly balloons to the size of a basketball, freezing organs.
The Metropolitan Police have told colleagues in the West Midlands to be on the lookout for the blade, which is designed to kill sharks and bears.